Decodable indicia reading terminal with optical filter

ABSTRACT

A decodable indicia reading terminal can comprise a housing including a housing window, a multiple pixel image sensor disposed within the housing, an imaging lens configured to focus an image of decodable indicia on the image sensor, an optical bandpass filter disposed in an optical path of light incident on the image sensor, an analog-to-digital (A/D) converter configured to convert an analog signal read out of the image sensor into a digital signal representative of the analog signal, and processor configured to output a decoded message data corresponding to the decodable indicia by processing the digital signal.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims the benefit of U.S. patent applicationSer. No. 14/159,603 for a Decodable Indicia Reading Terminal withOptical Filter filed Jan. 21, 2014 (and published May 15, 2014 as U.S.Patent Publication No. 2014/0131445), now U.S. Pat. No. 9,224,025, whichclaims the benefit of U.S. patent application Ser. No. 13/170,104 for aDecodable Indicia Reading Terminal with Optical Filter filed Jun. 27,2011 (and published Dec. 27, 2012 as U.S. Patent Publication No.2012/0325911), now U.S. Pat. No. 8,636,215. U.S. patent application Ser.No. 13/309,195 for an Optical Filter for Image and Barcode Scanningfiled Dec. 1, 2011 (and published Dec. 27, 2012 as U.S. PatentPublication No. 2012/0325912), now U.S. Pat. No. 8,640,960, also claimsthe benefit of U.S. patent application Ser. No. 13/170,104. Each of theforegoing patent applications, patent publications, and patents ishereby incorporated by reference in its entirety.

FIELD OF THE INVENTION

This invention relates generally to decodable indicia reading terminalsand, more specifically, to optical indicia reading terminals comprisingan optical filter.

BACKGROUND

The use of optical indicia, such as bar code symbols, for product andarticle identification is well known in the art. Decodable indiciareading terminals are available in multiple varieties. For example,minimally featured bar code reading terminals devoid of a keyboard anddisplay are common in point of sale applications. Decodable indiciareading terminals devoid of a keyboard and display are available in therecognizable gun style form factor having a handle and trigger button(trigger) that can be actuated by an index finger. Decodable indiciareading terminals having keyboards and displays are also available.Keyboards and display equipped decodable indicia reading terminals arecommonly used in shipping and warehouse applications, and are availablein form factors incorporating a display and keyboard. In a keyboard anddisplay equipped decodable indicia reading terminal, a trigger buttonfor actuating the output of decoded messages is typically provided insuch locations as to enable actuation by a thumb of an operator.Keyboard and display equipped decodable indicia reading terminals areavailable in a form in which the keyboard and display are commonlyprovided by a display having an associated touch panel. Decodableindicia reading terminals in a form devoid of a keyboard and display orin a keyboard and display equipped form are commonly used in a varietyof data collection applications including point of sale applications,shipping applications, warehousing applications, security check pointapplications, and patient care applications. Decodable indicia readingterminals are also available in a presentation reader form factor. Suchterminals can be mounted at a checkout station. Some bar code readingterminals are adapted to read bar code symbols including one or more ofone-dimensional (1D) bar codes, and two-dimensional (2D) bar codes.

One common type of scan engine found in hand-held and retail scanners isthe digital imager, which includes 1D (linear) imagers and 2D (area)imagers. Digital imagers typically utilize a lens to focus the image ofthe bar code onto a multiple pixel image sensor, which often is providedby a CMOS-based or CCD-based image sensor that converts light signalsinto electric signals. A light source such as light emitting diodes(LEDs) simultaneously illuminate all of the bars and spaces of a barcode symbol in order to capture an image for recognition and decodingpurposes.

SUMMARY

In one embodiment, there is provided a decodable indicia readingterminal which can comprise a housing including a housing window, amultiple pixel image sensor disposed within the housing, an imaging lensconfigured to focus an image of decodable indicia on the image sensor,an optical bandpass filter disposed in an optical path of light incidenton the image sensor, an analog-to-digital (A/D) converter configured toconvert an analog signal read out of the image sensor into a digitalsignal representative of the analog signal, and a processor configuredto output a decoded message data corresponding to the decodable indiciaby processing the digital signal. The optical bandpass filter can beconfigured to pass light of two or more selected ranges of wavelengthsand to attenuate light of wavelengths outside of said two or moreselected ranges.

BRIEF DESCRIPTION OF THE DRAWINGS

The features described herein can be better understood with reference tothe drawings described below. The drawings are not necessarily to scale,emphasis instead generally being placed upon illustrating the principlesof the invention. In the drawings, like numerals are used to indicatelike parts throughout the various views.

FIGS. 1-2 schematically illustrate embodiments of a decodable indiciareading terminal;

FIG. 3 is a component diagram of one embodiment of a decodable indiciareading terminal;

FIGS. 4-6 schematically illustrate transmission diagrams of opticalbandpass filters employed by decodable indicia reading terminalaccording to several illustrative embodiments.

DETAILED DESCRIPTION

In an illustrative embodiment, shown in FIG. 1, there is provided anoptical indicia reading terminal 100 including a housing 52 comprising ahead portion 54 and a handle portion 56, the latter further comprising ahand grip 58 and a trigger 60. The trigger 60 can be used to initiatesignals for activating frame readout and/or certain decoding processes.Other components of the optical indicia reading terminal 100 can bedisposed within the housing 52. For example, an image sensor 62 can bedisposed in the head portion 54 behind a housing window 63. The imagesensor 62 can be configured to output an electrical signalrepresentative of light incident on the image sensor.

The optical indicia reading terminal 100 can further comprise an I/Ointerface which in the illustrative embodiment of FIG. 1 can becommunicatively coupled to a wired connection 66. The I/O interface canbe used to communicatively couple the optical indicia reading terminal100 to a companion device 68 such as a register and/or peripheral datacapture devices in a point-of-sale (POS) application. Otherconfigurations of the I/O interface may utilize wireless communicationtechnology and/or contact-type features that do not require wires and/orwired connection 66. In certain applications of the indicia readingterminal 100 for example, the companion device 68 may be provided by adocking station with corresponding mating contacts and/or connectorsthat are useful to exchange power and data, including image datacaptured by the imaging module 62.

Although not incorporated in the illustrative embodiment of FIG. 1, theoptical indicia reading terminal 100 can also comprise a number ofperipheral devices, including a display for displaying such informationas image frames captured by the terminal, a keyboard, and a pointingdevice.

The optical indicia reading terminal 100 can be used, for example, forbar code reading and decoding in POS and other applications. A skilledartisan would appreciate the fact that other uses of optical indiciareading terminal 100 are within the scope of this disclosure.

A product having decodable indicia can be scanned by the optical indiciareading terminal 100. As used herein, “decodable indicia” is intended todenote a representation of a message, such as the representation in abar code symbology of a character string comprising alphanumeric andnon-alphanumeric characters. Decodable indicia can be used to conveyinformation, such as the identification of the source and the model of aproduct, for example in a UPC bar code that comprises twelve encodedsymbol characters representing numerical digits. The optical indiciareading terminal can be configured to output a decoded message datacorresponding to the decodable indicia.

While FIG. 1 illustrates a hand held housing, a skilled artisan wouldappreciate the fact that other types and form factors of terminalhousings are within the scope of this disclosure. For example, in oneembodiment schematically shown in FIG. 2, the decodable indicia readingterminal can be incorporated into a POS workstation with a presentationhousing. The workstation 1010 can include a horizontal countertop 1012for placement of products to be scanned. A bioptic scanner 1014 mountedwithin the countertop 1012 can include a first housing portion 1016 anda second housing portion 1018 which can project from one end of thefirst housing portion in a substantially orthogonal manner. In oneembodiment, the first housing portion 1016 can comprise a laser-basedindicia scanning terminal and the second housing portion 1018 cancomprise an imager-based terminal. The countertop 1012 can include anoptically transparent (e.g., glass) horizontal-scanning window 1020mounted flush with the checkout counter, covered by an imaging windowprotection plate 1022 which can be provided with a pattern of apertures1024 a. The second housing portion 1018 can further include avertical-scanning window 1026 behind which an imager-based indiciareading terminal 1028 can be housed. A skilled artisan would appreciatethe fact that other ways of disposing the scanners and scanning windowsare within the scope of this disclosure.

In POS and many other applications, one of the key challenges forimaging devices is the requirement of intense illumination. Themagnitude of illumination intensity is directly correlated to the motiontolerance performance of the bar code scanning/imaging device. Device'suser satisfaction depends on high motion tolerance demonstrated by thedevice, while requiring the lowest possible perceived illuminationintensity.

In order to reduce the perceived illumination intensity, the housingwindow of a bar code scanning/imaging device can be configured to onlypass the light in the red spectrum region. The benefits of such approachwould include more stable exposure and more balanced images. However, ared housing window would attenuate the light in other (non-red) spectrumregions, thus producing a monochrome image and potentially causing lossof image content. A clear housing window, on the other hand, would passall the color spectrum unfiltered but will lead to a more intenseperceived illumination.

In order to overcome the above described challenge, the optical indiciareading terminal can in one embodiment comprise an optical bandpassfilter disposed in an optical path of light incident on the image sensorand configured to balance the color content and the perceivedillumination. In one embodiment, the optical bandpass filter can beconfigured to pass light of one or more selected ranges of wavelengthsand to attenuate light of wavelengths outside of the selected ranges. Inanother embodiment, the optical indicia reading terminal can comprise amulti-band optical bandpass filter that can be configured to pass lightof two or more selected ranges of wavelengths and to attenuate light ofwavelengths outside of the selected ranges. An optical indicia readingterminal having a multi-band optical bandpass filter can be used forboth monochrome and color applications,

FIG. 3 illustrates a block diagram of one embodiment of an opticalindicia reading terminal. The optical indicia reading terminal 100 cancomprise a multiple pixel image sensor 62, which in one embodiment canbe provided by a charge-coupled device (CCD) image sensor. In anotherembodiment, the image sensor 62 can be provided by a complementarymetal-oxide-semiconductor (CMOS) image sensor. A skilled artisan wouldappreciate the fact that other types of image sensors are within thescope of this disclosure.

The image sensor 62 can comprise a multiple pixel image sensor array3074 having pixels arranged in rows and columns of pixels, columncircuitry 3076, and row circuitry 3078. Associated with the image sensor62 can be amplifier circuitry 3080, and an analog-to-digital (A/D)converter 3082 which can be configured to convert image information inthe form of analog signals read out of multiple pixel image sensor array3074 into image information in the form of digital signals. Alsoassociated with the image sensor 62 can be timing and control circuit3084 for use in controlling, e.g., the exposure period of image sensor62, and/or gain applied to the amplifier 3080. The noted circuitcomponents 62, 3080, 3082, and 3084 can be packaged into a common imagesensor integrated circuit 3086. In one example, image sensor integratedcircuit 3086 can be provided by an MT9V022 mage sensor integratedcircuit available from Micron Technology, Inc. In another example, imagesensor integrated circuit 3086 can incorporate a Bayer pattern filler.

In operation, image signals can be read out of image sensor 62,converted and stored into one or more memories such as 3090. A memory3092 can include RAM 3090, a nonvolatile memory such as EPROM 3094, anda storage memory device 3096 such as may be provided by a flash memoryor a hard drive memory.

In one embodiment, the optical indicia reading terminal 100 can includea processor 3088 which can be configured to read out image data storedin memory 3092 and subject such image data to various image processingalgorithms. In one embodiment, the processor 3088 can be configured tooutput a decoded message data corresponding to scanned decodable indiciaby processing a digital signal representative of an analog signal readout of the image sensor 62.

Optical indicia reading terminal 100 can also include a direct memoryaccess unit (DMA) 3098 for routing image information read out from imagesensor 62 that has been subject to conversion to RAM 3090. In anotherembodiment, the optical indicia reading terminal 100 can employ a systembus providing for bus arbitration mechanism (e.g., a PCI bus) thuseliminating the need for a central DMA controller. A skilled artisanwould appreciate that other embodiments of the system bus architectureand/or direct memory access components providing for efficient datatransfer between the image sensor 62 and RAM 3090 are within the scopeof this disclosure.

The optical indicia reading terminal 100 can also include an imaginglens assembly 3100 for focusing an image of the decodable indicia 1032onto image sensor 62. Imaging light rays can be transmitted about anoptical axis 3102. The optical indicia reading terminal 100 can alsoinclude an illumination assembly 3104 comprising one or moreillumination light source banks 3106 comprising one or more LEDS forgenerating an illumination pattern substantially corresponding to thefield of view of the image sensor 62.

In one embodiment, each illumination LED can be formed by multiple dieshaving different spectral characteristics. In another embodiment, one ormore illumination LEDs can have different spectral characteristics.Hence, the spectrum of the light irradiated upon the optical indicia canbe formed by multiple different dies with different spectralcharacteristics on a single LED, or by multiple LEDs with differentspectral characteristics. In a further aspect, the spectrum of the lightirradiated upon the indicia can vary at different area of the indicia.

In one embodiment, the optical indicia reading terminal 100 can alsoinclude an aiming pattern light source bank 3108 comprising one or moreLEDs for generating an aiming pattern. In operation, the terminal 100can be oriented relatively to the product 3030 by an operator of theterminal 100 in such manner that the aiming pattern is projected on theencoded symbol character 3032.

In another aspect, the optical indicia reading terminal can furthercomprise an optical bandpass filter 3110 disposed in an optical pass oflight incident on the image sensor. The optical bandpass filter 3110 canbe configured to pass light of one or more selected ranges ofwavelengths and to attenuate light of wavelengths outside of theselected ranges. In one embodiment, the optical bandpass filter 3110 canbe configured to pass light of two or more selected ranges ofwavelengths and to attenuate light of wavelengths outside of theselected ranges.

In the illustrative embodiment of FIG. 3, the optical bandpass filter3110 can be disposed between the housing window 63 and the imaging lensassembly 3100. In another embodiment, the filter module 3110 can bedisposed, for example, but not limited to, between the imaging lensassembly 3100 and the image sensor 62, at a surface of the imaging lensassembly 3100, or at a surface of the micro-lens 3077 of the imagesensor 62. In a yet another embodiment, the filter module 3110 can bebuilt-in, for example, but not limited to, into the imaging lensassembly 3100, into the micro-lens 3077 of the image sensor 62, or intothe housing window 63.

In one embodiment, the optical bandpass filter 3110 can be manufacturedusing one or more multi-layer coatings which can be applied to anoptically transparent substrate.

In another embodiment, the optical bandpass filter 3110 can bemanufactured using periodic structures which can be formed by a singlematerial or multiple different materials with repeating features in oneor more dimensions. A skilled artisan would appreciate the fact thatother technologies of manufacturing optical bandpass filter are withinthe scope of this disclosure.

In a further aspect, the optical bandpass filter 3110 can be describedby the following characteristics:

Center Wavelength (CWL) is the wavelength at the center of the passband;

Full Width at Half Maximum (FWHM) is the bandwidth at 50% of the maximumtransmission;

peak Transmission (T) is the wavelength of maximum transmission; and

blocking range is the spectral region in which the filter does nottransmit.

In one embodiment, the CWL of the optical bandpass filter 3110 can beconfigured to match the illumination light spectrum. In one illustrativeembodiment shown in FIG. 4, the optical bandpass filter can have a CWLequal to 635 nm, and FWHM equal to 65 nm to accommodate the ray angle aswell as LED variation (for amber LED with peak wavelength of 624 nm,dominant wavelength of 617 nm, tolerance +7/−5 nm).

In another embodiment, the optical bandpass filter can include anadditional passband 410 which can be configured, for example, to match ablue peak of the white light, as shown in FIG. 5. In another embodiment,the optical bandpass filter can include an additional passbandconfigured to match the backlight emitting by a screen of a portablecommunication device, for example, but not limited to, PDA or cellularphone.

In a yet another embodiment, the optical bandpass filter can include twoadditional passbands 510, 520 which can be configured, for example, tomatch a blue and a green peak of the white light, as shown in FIG. 6.

In a further aspect, the optical indicia reading terminal 100 caninclude various control circuits. Lens assembly 3100 can be controlledwith use of lens assembly control circuit 3114 and the illuminationassembly 3104 comprising illumination pattern light source bank 3106 andaiming pattern light source bank 3108 can be controlled with use ofillumination assembly control circuit 3116. Filter module 3110 can becontrolled with use of a filter module control circuit 3118, which canbe coupled to the actuator assembly 3112. Lens assembly control circuit3114 can send signals to lens assembly 3100, e.g., for changing a focallength and/or a best focus distance of lens assembly 3100. Illuminationassembly control circuit 3116 can send signals to illumination patternlight source bank 3106, e.g., for changing a level of illuminationoutput.

In a further aspect, the optical indicia reading terminal 100 caninclude various interface circuits for coupling several of theperipheral devices to system address/data bus (system bus) bus 3120, forcommunication with the processor 3088 also coupled to system bus 3120.The optical indicia reading terminal 100 can include interface circuit3122 for coupling image sensor timing and control circuit 3084 to systembus 3120, interface circuit 3124 for coupling the lens assembly controlcircuit 3114 to system bus 3120, interface circuit 3126 for coupling theillumination assembly control circuit 3116 to system bus 3120, interfacecircuit 3128 for coupling a display 3130 to system bus 3120, interfacecircuit 3132 for coupling a keyboard 3134, a pointing device 3136, andtrigger 3060 to system bus 3120, and interface circuit 3138 for couplingthe filter module control circuit 3118 to system bus 3120.

In a further aspect, the optical indicia reading terminal 100 caninclude one or more I/O interfaces 3140, 3142 for providingcommunication with external devices (e.g., a cash register server, astore server, an inventory facility server, a local area network basestation, a cellular base station). I/O interfaces 3140, 3142 can beinterfaces of any combination of known computer interfaces, e.g.,Ethernet (IEEE 802.3), USB, IEEE 802.11, Bluetooth, CDMA, and GSM, andmay couple with processors, such as interface microcontrollers, andmemories to carry out some or all the functions described herein.

While the present invention has been described with reference to anumber of specific embodiments, it will be understood that the truespirit and scope of the invention should be determined only with respectto claims that can be supported by the present specification. Further,while in numerous cases herein wherein systems and apparatuses andmethods are described as having a certain number of elements it will beunderstood that such systems, apparatuses and methods can be practicedwith fewer than the mentioned certain number of elements. Also, while anumber of particular embodiments have been described, it will beunderstood that features and aspects that have been described withreference to each particular embodiment can be used with each remainingparticularly described embodiment.

A sample of systems and methods that are described herein follows:

A1 A decodable indicia reading terminal comprising:

-   -   a housing including a housing window;    -   a multiple pixel image sensor disposed within said housing;    -   an imaging lens configured to focus an image of decodable        indicia on said image sensor;    -   an optical bandpass filter disposed in an optical path of light        incident on said image sensor, said optical bandpass filter        configured to pass light of two or more selected ranges of        wavelengths and to attenuate light of wavelengths outside of        said two or more selected ranges;    -   an analog-to-digital (A/D) converter configured to convert an        analog signal read out of said image sensor into a digital        signal representative of said analog signal, said analog signal        representative of light incident on said image sensor; and    -   a processor configured to output a decoded message data        corresponding to said decodable indicia by processing said        digital signal.

A2. The optical indicia reading terminal of A1 configured to acquireimages in a monochrome mode and in a color mode.

A3. The optical indicia reading terminal of A1, wherein said opticalbandpass filter is disposed between said housing window and said imaginglens.

A4. The optical indicia reading terminal of A1, wherein said opticalbandpass filter is disposed said imaging lens assembly and said imagesensor.

A5. The optical indicia reading terminal of A1, wherein said opticalbandpass filter is disposed at a surface of said imaging lens assembly.

A6. The optical indicia reading terminal of A1, wherein said multiplepixel image sensor comprises a micro-lens; and

-   -   wherein said optical bandpass filter is disposed at a surface of        said micro-lens.

A7. The optical indicia reading terminal of A1, wherein said opticalbandpass filter is built-in into said imaging lens assembly.

A8. The optical indicia reading terminal of A1, wherein said multiplepixel image sensor comprises a micro-lens; and

-   -   wherein said optical bandpass filter is built-in into said        micro-lens.

A9. The optical indicia reading terminal of A1, wherein said opticalbandpass filter is built-in into said housing window.

A10. The optical indicia reading terminal of A1, wherein said filtercomprises a multi-layer coating.

A11. The optical indicia reading terminal of A1, wherein said filtercomprises periodic structures.

A12. The optical indicia reading terminal of A1, further comprising oneor more illumination LEDs configured to illuminate a substrate bearingdecodable indicia.

A13. The optical indicia reading terminal of A1, further comprising oneor more illumination LEDs having different spectral characteristics,said one or more illumination LEDs configured to illuminate a substratebearing decodable indicia.

A14. The optical indicia reading terminal of A1, further comprising oneor more illumination LEDs, each illumination LED of said one or moreillumination LEDs comprising one or more dies having different spectralcharacteristics;

-   -   wherein said one or more illumination LEDs are configured to        illuminate a substrate bearing decodable indicia.

A15. The optical indicia reading terminal of A1, further comprising oneor more illumination LEDs configured to illuminate a substrate bearingdecodable indicia, by emitting light having an illumination lightspectrum;

-   -   wherein said illumination light spectrum varies at different        areas of said substrate.

A16. The optical indicia reading terminal of A1, further comprising oneor more illumination LEDs configured to illuminate said substrate, byemitting light having an illumination light spectrum;

-   -   wherein a center wavelength of said optical bandpass filter is        configured to match said illumination light spectrum.

A17. The optical indicia reading terminal of A1, wherein said opticalbandpass filter includes a passband configured to match a backlightemitted by a portable communication device.

A18. The optical indicia reading terminal of A1, wherein said housing isprovided by a hand held housing.

A19. The optical indicia reading terminal of A1, wherein said housing isprovided by a point-of-sale workstation housing.

A20. The optical indicia reading terminal of A1 wherein said housing isprovided by a presentation housing.

While the present invention has been described with reference to anumber of specific embodiments, it will be understood that the truespirit and scope of the invention should be determined only with respectto claims that can be supported by the present specification. Further,while in numerous cases herein wherein systems and apparatuses andmethods are described as having a certain number of elements it will heunderstood that such systems, apparatuses and methods can be practicedwith fewer than or greater than the mentioned certain number ofelements. Also, while a number of particular embodiments have beendescribed, it will be understood that features and aspects that havebeen described with reference to each particular embodiment can be usedwith each remaining particularly described embodiment.

1. An apparatus comprising: an image sensor configured to output asignal representative of incident on the image sensor via an opticalpath; an optical bandpass filter disposed in the image sensor's opticalpath so that light incident on the image sensor passes through theoptical bandpass filter and is subject to bandpass filtering by theoptical bandpass filter in common wavelength ranges, the opticalbandpass filter configured for passing of two or more selectedwavelength ranges and for attenuating light having a wavelength outsidethe two or more selected wavelength ranges.
 2. The apparatus of claim 1,wherein the apparatus is configured for acquiring images in a monochromemode and in a color mode.
 3. The apparatus of claim 1, wherein: theimage sensor comprises a micro-lens; and the optical bandpass filter isdisposed at a surface of the micro-lens.
 4. The apparatus of claim 1,wherein: the image sensor comprises a micro-lens; and the opticalbandpass filter is built into the micro-lens.
 5. The apparatus of claim1, comprising a window, wherein the optical bandpass filter is builtinto the window.
 6. The apparatus of claim 1, wherein the opticalbandpass filter comprises a multi-layer coating.
 7. The apparatus ofclaim 1, wherein the optical bandpass filter comprises periodicstructures.
 8. The apparatus of claim 1, wherein the optical bandpassfilter includes a passband configured to match a backlight emitted by aportable communication device.
 9. The apparatus of claim 1, comprising ahand held housing.
 10. The apparatus of claim 1, comprising apresentation housing.
 11. An apparatus comprising: an image sensorconfigured to output a signal representative of light incident on theimage sensor via an optical path; a housing window disposed in the imagesensor's optical path; an imaging lens for focusing light onto the imagesensor, the imaging lens being disposed in the image sensor's opticalpath between the housing window and the image sensor; an opticalbandpass filter disposed in the image sensor's optical path so thatlight incident on the image sensor passes through the optical bandpassfilter and is subject to bandpass filtering by the optical bandpassfilter in common wavelength ranges, the optical bandpass filterconfigured for passing light of two or more selected wavelength rangesand for attenuating light having a wavelength outside the two or moreselected wavelength ranges.
 12. The apparatus of claim 11, wherein theoptical bandpass filter is disposed between the housing window and theimaging lens.
 13. The apparatus of claim ii, wherein the opticalbandpass filter is disposed between the imaging lens and the imagesensor.
 14. The apparatus of claim 11, wherein the optical bandpassfilter is disposed at a surface of the imaging lens.
 15. The apparatusof claim wherein the optical bandpass filter is built into the imaginglens.
 16. An apparatus comprising: an image sensor having afield ofview, the image sensor being configured to output a signalrepresentative of light incident on the image sensor via an opticalpath; an optical bandpass filter disposed in the image sensor's opticalpath so that light incident on the image sensor passes through theoptical bandpass filter and is subject to bandpass filtering by theoptical bandpass filter in common wavelength ranges, the opticalbandpass filter configured for passing light of two or more selectedwavelength ranges and for attenuating light having a wavelength outsidethe two or more selected wavelength ranges; an illumination assembly forgenerating an illumination pattern substantially corresponding to thefield of view of the image sensor.
 17. The apparatus of claim 16,wherein the illumination assembly comprises two or more illuminationLEDs, each of the two or more illumination LEDs having differentspectral characteristics.
 18. The apparatus of claim 16, wherein theillumination assembly comprises two or more illumination LEDs, each ofthe two or more illumination LEDs comprising dies having differentspectral characteristics.
 19. The apparatus of claim 16, wherein theillumination assembly comprises an illumination LED for illuminating asubstrate bearing decodable indicia by emitting light having anillumination spectrum that varies at different areas of the substrate.20. The apparatus of claim 6, wherein the illumination assemblycomprises an illumination LED for emitting light having an illuminationspectrum that matches a selected wavelength range of the opticalbandpass filter.